1. Field of the Invention
The present invention relates to a key operation detection unit of an electronic keyboard instrument, which includes a detector that detects a key depression operation while generating a reaction force when the key depression operation is carried out.
2. Description of the Related Art
Conventionally, a key operation detection unit (switch unit) is known, which comprises a detector (switch) that detects a key depression operation and is moved by a moving member with the key depression operation (see for example, Japanese Laid-open Patent Publication (Kokai) No. H04-272626). This key operation detection unit is provided with two detectors each of which includes a fixed contact formed on a base plate and a movable contact formed on a resilient urging member which is driven by a key actuator. Upon key depression operation, the movable and fixed contacts of these two detectors are closed with a time difference. In addition to the resilient urging member, there is provided a resilient member that generates a reaction force when depressed with the key depression operation.
In the key operation detection unit, the resilient urging member of each detector also generates a reaction force upon key depression operation. The generations of reaction forces from the detectors take place with a time difference. The reaction forces from the detectors are added sequentially in the key depression stroke, and hence the load applied to the key increases stepwise.
When influences of the reaction forces from the detectors upon key touch feeling are not adequately considered in the aforementioned key operation detection unit, a large stepwise variation in the key load gives a key touch feeling which is quite different from that of an acoustic piano, resulting in an unnatural, unsatisfactory key touch feeling.